VALIDATION OF THE POLARIS CANDU EXTENSION FOR LATTICE PHYSICS

Polaris is a new lattice physics package, introduced in version 6.2 of the SCALE package. It uses a method of characteristics transport solver and the embedded self-shielding method. It is able to model light water reactor systems with a minimal amount of input. The goal of this project is to include support for CANDU models in Polaris for the next version of SCALE. So far, the model has been implemented and shown to give results with reasonable agreement to other SCALE sequences. This study extends the model to a reflector model, and shows that most quantities agree well with other codes. Some quantities, such as keff and assembly discontinuity factors, are sensitive to meshing. This study also performs a correlation between the TRITON and Polaris sequences using Sampler to perturb the nuclear data. Overall, there is good agreement between the two codes, though coolant void reactivity is only moderately correlated, likely due to the differences in resonance self-shielding methods. Additionally, this work shows that a coarser mesh can be used to speed up uncertainty calculations compared to the mesh used for a best estimate. Finally, this work shows that the mass lumping feature in CENTRM significantly affects heavy water moderated calculations, whether using TRITON or calculating self-shielding factors, and thus should be disabled for heavy water calculations.

Radiation protection to patients in radiology: A review study

The present paper aims at reviewing different shielding methods used for patients in medical imaging and investigating their merits and demerits. These techniques are generally classified into two groups including in-plane and out-of-plane shielding. Bismuth (Bi) shielding is a conventional in-plane shielding method used during CT examinations to protect radiosensitive organs. This method has reduced radiosensitive organs dose by about 34–68% during different CT examinations. However, it causes considerable degrading effects on image quality and for this reason AAPM recommended against its application in 2017. Recently, another in-plane shielding, named Saba shielding, introduced wherein all the shortcomings and deficits of Bi shielding have been resolved or fixed. Saba shielding reduces radiosensitive organs dose by about 50% without degrading image quality. Out-of-plane shields can decrease the patient dose by more than 55%. However, due to the low dose of the scattered radiation received by out-of-plane organs, in the case of applying out-of-plane shields such as gonad or thyroid shields, the risk and benefit of their usage should be evaluated.

EMERGING AREAS OF SHIELDING RESEARCH—A BIRD’S EYE VIEW

Shielding analysis and design are important tools for ensuring that humans and the environment are protected from the detrimental effects of high levels of radiation. The fundamental principles and methodologies for shielding analysis and design, especially for reactor applications, have been developed and refined since the 1940s and the beginning of nuclear power research programs in Canada and internationally. Other applications are gaining importance due to both increased need and technological advances. In this work, a high-level survey of emerging areas in shielding research and development is provided. Areas of topical interest include remote reactor monitoring, source reconstruction and inverse shielding methods, waste management and decommissioning applications, accelerator, cyclotron, and other advanced medical shielding applications, space exploration, and new materials development. Each of these areas of interest is evaluated based on current capacity of the research community. They are also evaluated in terms of the benefits for the scientific community and industry arising from performing research including development of new technologies and techniques.